A facile and green strategy to fabricate luminescent Fe:ZnSe nanocrystals and their structural and optical properties

Semiconductor nanocrystals have traditionally been synthesized using pyrophoric, toxic, and expensive reagents, which are not appropriate for industrial synthesis or application in the future. Herein, we report a facile and green route for the synthesis of highly emissive and water-soluble Fe:ZnSe nanocrystals by using low-cost, and environmentally friendly precursors and solvents. The capping of Fe:ZnSe nanocrystals by mercaptoacetic acid ligand is evidenced by Fourier transform infrared spectroscopy. The Fe:ZnSe nanocrystals have a cubic zinc blende crystalline structure with an average particle size of ∼4 nm, which show blue shift in UV–vis absorption spectra compared to bulk ZnSe. The obtained nanocrystals are highly luminescent with a widely tunable photoluminescence (PL) emission window of 426–442 nm, with a narrow PL full width at half-maximum. The photoluminescence quantum yield of the corresponding nanocrystals is typically maintained at 20% or higher at room temperature without any post-synthesis treatment. The pH-dependent optical properties of those Fe:ZnSe nanocrystals are systemically investigated, and the underlying mechanism for the tunable luminescence properties of the as-prepared Fe:ZnSe nanocrystals is elucidated. Moreover, the protocol allows for a highly reproducible and effective synthesis, which is fully adaptable for mass production and can be easily employed to synthesize a variety of doped and alloyed nanocrystals.